58 research outputs found

    Experiments with recursive estimation in astronomical image processing

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    Recursive estimation concepts were applied to image enhancement problems since the 70's. However, very few applications in the particular area of astronomical image processing are known. These concepts were derived, for 2-dimensional images, from the well-known theory of Kalman filtering in one dimension. The historic reasons for application of these techniques to digital images are related to the images' scanned nature, in which the temporal output of a scanner device can be processed on-line by techniques borrowed directly from 1-dimensional recursive signal analysis. However, recursive estimation has particular properties that make it attractive even in modern days, when big computer memories make the full scanned image available to the processor at any given time. One particularly important aspect is the ability of recursive techniques to deal with non-stationary phenomena, that is, phenomena which have their statistical properties variable in time (or position in a 2-D image). Many image processing methods make underlying stationary assumptions either for the stochastic field being imaged, for the imaging system properties, or both. They will underperform, or even fail, when applied to images that deviate significantly from stationarity. Recursive methods, on the contrary, make it feasible to perform adaptive processing, that is, to process the image by a processor with properties tuned to the image's local statistical properties. Recursive estimation can be used to build estimates of images degraded by such phenomena as noise and blur. We show examples of recursive adaptive processing of astronomical images, using several local statistical properties to drive the adaptive processor, as average signal intensity, signal-to-noise and autocorrelation function. Software was developed under IRAF, and as such will be made available to interested users

    The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3

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    We investigate the relationship between black hole mass and host galaxy velocity dispersion for QSOs in Data Release 3 of the Sloan Digital Sky Survey. We derive black hole mass from the broad Hbeta line width and continuum luminosity, and the bulge stellar velocity dispersion from the [OIII] narrow line width. At higher redshifts, we use MgII and [OII] in place of Hbeta and [OIII]. For redshifts z < 0.5, our results agree with the black hole mass - bulge velocity dispersion relationship for nearby galaxies. For 0.5 < z < 1.2, this relationship appears to show evolution with redshift in the sense that the bulges are too small for their black holes. However, we find that part of this apparent trend can be attributed to observational biases, including a Malmquist bias involving the QSO luminosity. Accounting for these biases, we find ~0.2 dex evolution in the black hole mass-bulge velocity dispersion relationship between now and redshift z ~ 1.Comment: Accepted by ApJ, 15 pages, 9 figure

    A variability study of the Seyfert 2 galaxy NGC 6300 with XMM-Newton

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    We present the results of timing analysis of the XMM-Newton observation of the Seyfert 2 galaxy NGC 6300. The hard X-ray spectrum above 2 keV consists of a Compton-thin-absorbed power law, as is often seen in Seyfert 2 galaxies. We clearly detected rapid time variability on a time scale of about 1000 s from the light curve above 2 keV. The excess variance of the time variability (sigma2_RMS) is calculated to be ~0.12, and the periodogram of the light curve is well represented by a power law function with a slope of 1.75. In contrast with previous results from Seyfert 2 nuclei, these variability characteristics are consistent with those of Seyfert 1 galaxies. This consistency suggests that NGC 6300 has a similar black hole mass and accretion properties as Seyfert 1 galaxies. Using the relation between time variability and central black hole mass by Hayashida et al. (1998), the black hole mass of NGC 6300 is estimated to be ~2.8x10^5 Mo. Taking uncertainty of this method into account, the black hole mass is less than 10^7 Mo. Taking the bolometric luminosity of 3.3x10^43 erg/s into consideration, this yields an accretion rate of > 0.03 of the Eddington value, and comparable with estimates from Seyfert 1 galaxies using this method. The time variability analysis suggests that NGC 6300 actually has a Seyfert 1 nucleus obscured by a thick matter, and more generally provides a new pillar of support for the unified model of Seyfert galaxies based on obscuration.Comment: 11 pages, 6 figures, accepted for publication in Ap

    Deep CCD Surface Photometry of Galaxy Clusters I: Methods and Initial Studies of Intracluster Starlight

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    We report the initial results of a deep imaging survey of galaxy clusters. The primary goals of this survey are to quantify the amount of intracluster light as a function of cluster properties, and to quantify the frequency of tidal debris. We outline the techniques needed to perform such a survey, and we report findings for the first two galaxy clusters in the survey: Abell 1413, and MKW 7 . These clusters vary greatly in richness and structure. We show that our surface photometry reliably reaches to a surface brightness of \mu_v = 26.5 mags per arcsec. We find that both clusters show clear excesses over a best-fitting r^{1/4} profile: this was expected for Abell 1413, but not for MKW 7. Both clusters also show evidence of tidal debris in the form of plumes and arc-like structures, but no long tidal arcs were detected. We also find that the central cD galaxy in Abell 1413 is flattened at large radii, with an ellipticity of 0.8\approx 0.8, the largest measured ellipticity of any cD galaxy to date.Comment: 58 pages, 24 figures, accepted for publication in the Astrophysical Journal. Version has extremely low resolution figures to comply with 650k limit. High resolution version is available at http://burro.astr.cwru.edu/johnf/icl1.ps.gz Obtaining high resolution version is strongly reccomende

    Location of upper borders of cavities containing dust and gas under pressure in comets

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    The distance between the pre-impact surface of Comet 9P/Tempel 1 and the upper border of the largest cavity excavated during ejection of material after the collision of the impact module of the Deep Impact spacecraft with the comet is estimated to be about 5-6 metres if the diameter of the DI transient crater was about 150-200 m. The estimated distance was 4 m at the diameter was 100 m. This result suggests that cavities containing dust and gas under pressure located a few metres below surfaces of comets can be frequent.Comment: Monthly Notices of Royal Astronomical Society, 2012, in press, 7 page

    Influence of microorganisms on the underground metal constructions corrosion

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    Проаналізовано основні аспекти впливу ґрунтових мікроорганізмів на корозію підземних металоконструкцій (трубопроводи, нафтове обладнання). Вснановлено, що крім корозійно-механічної природи пошкодження труб підземних трубопроводів мають і біологічну складову. Вона спричиняє деструкцію захисного ізоляційного покриття під дією асоціатів ґрунтових мікроорганізмів. Доведено, що, корозійний процес нафтогазового обладнання слід розглядати не як лише фізико-хімічне явище процес, а обов’язково враховувати вплив біологічної деградації. Вплив біологічних міркоорганізмів зумовлює окрихчення сталей із подальшим утворенням пітингів та тріщиноподібних дефектів, які можуть спричинити катастрофічне руйнування трубопроводу. Модифікацією бітумно-полімерної мастики МБПІД-1 інгібіторами корозії з класу амінів (А) та четвертинних амонійних солей (ЧАС) отримано біостійкі інноваційні протикорозійні покриття та вивчено їх характеристики. Досліджено бактерицидну активність запропонованих інгібіторів. Адгезія стрічки до мастики не залежить від рецептури композицій ізоляційного покриття. Встановлено, що адгезія мастики до заґрунтованого металу була вищою порівняно з базовою композицією для рецептур з інгібітором (А) та інгібітором (ЧАС) на 36,0 та 24,0% відповідно. Проведено дослідно-промислові випробування розроблених біостійких покриттів у трасових умовах на магістральних газопроводах Західного та Південного регіонів. Результати випробувань підтвердили їх високу ефективність у забезпеченні протикорозійного та мікробіологічного захисту підземних металоконструкцій.Technical problem of the analysis of failure and evaluation of degradation of the structural materials mechanical properties after their operational degradation is of importance for all critical structures, for main oil pipelines in particular. Analysis of the condition of operated pipelines is focused on the condition of the outer surface of the pipe, including the protective properties of coatings and possible damage from the outer surface. However, the pipelines which have been used for a long time are often characterized by multiple corrosion damages of the internal surfaces of pipes, which should also be considered. Corrosion damage to the pipe steel is not a separate problem, but a complex degradation factor, as it causes material embrittlement and hydrogenation. The basic aspects of the soil microorganisms impact on corrosion of underground metal structures (pipelines, oil equipment) have been analysed. It was determined that beside corrosion-mechanic damages the underground pipelines are subject to biological degradation, which causes the failure of the protective insulating coating under associates of soil microorganisms. It was proved, that the corrosion process of gas equipment should be considered not only as a physical-chemical phenomenon process, but the biological degradation impact must be taken into account. The impact of biological microorganisms caused the embrittlement of steels with further pittings and crack- like defects, which can results in the failure of the pipeline. Modification of bitumen-polymer mastic MBPID -1 by corrosion inhibitor class of amines (A) and quaternary ammonium salts (QAS) has resulted in obtaining biostable innovative anticorrosive coating and studying of their characteristics. Bactericidal activity of the proposed inhibitors has been investigated. Adhesion to mastic tape does not depend on the formulation of compositions coating. It was established that adhesion of mastic to primed metal was higher than that compared with the base composition for recipes inhibitor (A) and inhibitor (QAS) by 36.0 and 24.0 %, respectively. A pilot- scale tests of the designed biostable coating in highway conditions of gas pipelines in Western and Southern regions have been carried out. The test results aproved their high efficiency in providing corrosion and microbiological protection of underground metal constructions

    Statistical Properties of Radio Emission from the Palomar Seyfert Galaxies

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    We have carried out an analysis of the radio and optical properties of a statistical sample of 45 Seyfert galaxies from the Palomar spectroscopic survey of nearby galaxies. We find that the space density of bright galaxies (-22 mag <= M_{B_T} <= -18 mag) showing Seyfert activity is (1.25 +/- 0.38) X 10^{-3} Mpc^{-3}, considerably higher than found in other Seyfert samples. Host galaxy types, radio spectra, and radio source sizes are uncorrelated with Seyfert type, as predicted by the unified schemes for active galaxies. Approximately half of the detected galaxies have flat or inverted radio spectra, more than expected based on previous samples. Surprisingly, Seyfert 1 galaxies are found to have somewhat stronger radio sources than Seyfert 2 galaxies at 6 and 20 cm, particularly among the galaxies with the weakest nuclear activity. We suggest that this difference can be accommodated in the unified schemes if a minimum level of Seyfert activity is required for a radio source to emerge from the vicinity of the active nucleus. Below this level, Seyfert radio sources might be suppressed by free-free absorption associated with the nuclear torus or a compact narrow-line region, thus accounting for both the weakness of the radio emission and the preponderance of flat spectra. Alternatively, the flat spectra and weak radio sources might indicate that the weak active nuclei are fed by advection-dominated accretion disks.Comment: 18 pages using emulateapj5, 13 embedded figures, accepted by Ap

    Remnant of a "Wet" Merger: NGC 34 and Its Young Massive Clusters, Young Stellar Disk, and Strong Gaseous Outflow

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    This paper presents new images and spectroscopy of NGC 34 (Mrk 938) obtained with the du Pont 2.5-m and Baade 6.5-m telescopes at Las Campanas, plus photometry of an HST archival V image. This Mv = -21.6 galaxy has often been classified as a Seyfert 2, yet recently published infrared spectra suggest a dominant central starburst. We find that the galaxy features a single nucleus, a main spheroid containing a blue central disk, and tidal tails indicative of two former disk galaxies. These galaxies appear to have completed merging. The remnant shows three clear optical signs that the merger was gas-rich ("wet") and accompanied by a starburst: (1) It sports a rich system of young star clusters, of which 87 have absolute magnitudes -10.0 > Mv > -15.4. Five clusters with available spectra have ages in the range 0.1-1.0 Gyr, photometric masses between 2x10^6 and 2x10^7 Msun, and are gravitationally bound young globulars. (2) The blue central disk appears to be young. It is exponential, can be traced to >10 kpc radius, and has a smooth structure and colors suggest- ing a dominant, ~400 Myr old poststarburst population. And (3), the center of NGC 34 drives a strong outflow of cool, neutral gas, as revealed by broad blueshifted Na I D lines. The mean outflow velocity of this gas is -620 km/s, while the maximum velocity reaches -1050 km/s. We suggest that NGC 34 stems from two recently merged gas-rich disk galaxies with an estimated mass ratio between 1/3 and 2/3. The remnant seems to have first experienced a galaxy-wide starburst that then shrank to its current central and obscured state. The strong gaseous outflow came last. (Abridged

    An up-conversion luminophore with high quantum yield and brightness based on BaF2_{2}:Yb3+^{3+},Er3+^{3+} single crystals

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    Up-conversion (UC) of near-infrared radiation to visible light has received much attention because of its use in the conversion of solar radiation, luminescence thermometry, biosensing, and anti-counterfeiting applications. However, the main issue hindering the successful utilization of UC is the relatively low quantum efficiency of the process. In order to design new UC systems with high quantum yield (ϕUC_{UC}) values, we synthesized two series of co-doped BaF2_{2} single crystals with nominal concentrations of Yb3+^{3+} (2–15 mol%)/Er3+^{3+} (2 mol%) as well as Yb3+^{3+} (3 mol%)/Er3+^{3+} (2–15 mol%). The highest ϕUC_{UC} value of 10.0% was demonstrated for the BaF2_{2}:Er3+^{3+} (2 mol%) and Yb3+^{3+} (3 mol%) sample under 490 W cm2^{-2} of 976 nm excitation. To study the natural limit of UC efficiency, quantum yield values upon direct excitation (ϕDS_{DS}) of the 4^{4}S3/2_{3/2}DS_{DS} ≤ 26%) levels were measured. Comparison of experimental values of quantum yields to the ones obtained using Judd–Ofelt theory reveals strong quenching of the 4^{4}S3/2_{3/2} state for all investigated compositions. In addition, we observed an unusually strong contribution of the Er3+^{3+}:4I9/2_{9/2} excited state to both UC and down-shifting luminescent processes. This contribution becomes possible due to the very low maximum phonon energy of BaF2_{2} crystals (240 cm1^{-1})

    Kinematic Linkage Between the Broad and Narrow Line Emitting Gas in AGN

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    We investigate the radial velocity difference between the [OIII]5007,4959 and H-beta lines for a sample of 200 low redshift AGN. We identify seven objects showing an [OIII]5007 blueshift relative to H-beta with amplitude larger than 250 km/s (blue "outliers"). These line shifts are found in sources where the broad high ionization lines (e.g. CIV1549) also show a large systematic blueshift. Such blueshifts occur only in the population A region of the Eigenvector 1 parameter domain (that also contains NLSy1 sources). We suggest that [OIII] blueshifts are also associated with the high ionization outflow originating in these sources. This is a direct kinematic linkage between narrow and broad line emitting gas.Comment: accepted for publication by ApJ Let
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